I don't think it's about how simple it is. It's about the fact that some of us care deeply enough to care for creatures that have no way of voicing their discomforts, no way of helping themselves.
It's plain and simply the fact that someone gave enough of their time to help an injured living creature when it has no way of expressing gratitude or returning the favor in any way. It's an entirely selfless act. I've done some work in animal conservation and honestly there's no greater feeling than seeing an animal be able to behave as it was born to.

To be fair you can say the same thing about people who lose "faith in humanity" easily . "OMG a lot of 14 year old girls like justin beiber i lose faith" or "Ahh look at that 13 yr old swagfag with his snapback I lose fiath now cause teenager r dum".